The field of molecular electronics relies on ordered placement of molecules on a supporting substrate, which is often an electrode of an electronic device. For most applications, the molecules should have a definite orientation or be oriented with respect to the substrate plane, often perpendicular to it. Molecular films are often formed by Langmuir-Blodgett techniques to obtain a uniform monolayer or multi-layer film. However, the orientation of the molecules is often difficult to control using Langmuir-Blodgett techniques until carefully refined for each combination of molecule and substrate and even then may be complicated by domains. A more robust method of aligning the molecules is needed using a technique that is less sensitive to the particular molecule being used. In addition, some applications require molecules to be spaced (separated) from each other; this cannot be readily accomplished by Langmuir-Blodgett techniques.
One approach to providing spaced holes in a substrate (silicon nitride-coated silicon) is disclosed by M. Park et al, “Block Copolymer Lithography: Periodic Arrays of ˜1011 Holes in 1 Square Centimeter”, Science, Vol. 276, pp. 1401-1404 (30 May 1997). However, the block copolymer mask is easily ablated during reactive ion etching, thus limiting this approach in the depth of the holes that can be formed. Further, the block copolymers that are used are not commercially available, and must be synthesized for each use, which is inconvenient for use outside the laboratory.